Effects of web opening on the Behavior of Reinforced Concrete T-Beams

Abstract

In construction of modern buildings, the presence of openings became a necessary nowadays in order to accommodate many pipes and ducts required for the different services. On the other hand, the presence of these openings in RC T- beams affects their structural behavior. Because of the change in the beam section the corners of the opening are subjected to large concentration of stress, possibly producing cracks in the beam. The region nearby the openings is measured as the weaker part of the beam. In this study, a three-dimensional nonlinear finite element analysis using ABAQUS program had been employed to simulate simply supported reinforced concrete T-beams with and without web openings, which was subjected to concentrated load at mid span. Four study parameters were considered, including effect of size of circular web opening, shape of web opening, location of web opening and number of web opening (one and two) on the behavior of the RC T-beams. To verify whether finite element simulation process is correct finite element result was compared with experimental test and show good agreement. T-Beams were simulated to obtained the load deflection relationship and ultimate load and compare them with solid reference one. Result obtained from this study showed that reinforced concrete T- beam with small circular web opening of dimeter 50mm or 21% of web depth has small effect (2.9% reduction) but, circular web opening of dimeter 140mm or 60% of web depth has large effect (25.8% reduction) on load carrying capacity of reinforced concrete T- beam. The presence of web opening at 300mm from support of reinforced concrete T- beam reduce load carrying capacity up to 25% and at 750mm from support reduce load carrying capacity up to14.2% in comparison with control beam. From square, rectangular and circular shape of opening circular one has less effect and best shape of opening and regarding location of opening, web opening at 750mm has less effect on reduction in strength of T-beam. Placing two web opening in both sides of the supports was better than one opening but effect of number of opening (one and two) is small at all when compare with shape, size and location of web openings. Finally, circular web openings are highly recommended.